Re: [PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting

[Vincent Guittot <vincent.guittot@linaro.org>]

On Fri, 18 Jan 2019 at 11:42, Vincent Guittot
<vincent.guittot@linaro.org> wrote:
>
> Hi Guenter,
>
> Le Thursday 17 Jan 2019 à 14:16:28 (-0800), Guenter Roeck a écrit :
> > On Fri, Dec 21, 2018 at 11:33:56AM +0100, Vincent Guittot wrote:
> > > From: Thara Gopinath <thara.gopinath@linaro.org>
> > >
> > > This patch replaces jiffies based accounting for runtime_active_time
> > > and runtime_suspended_time with ktime base accounting. This makes the
> > > runtime debug counters inline with genpd and other pm subsytems which
> > > uses ktime based accounting.
> > >
> > > timekeeping is initialized before pm_runtime_init() so ktime_get() will
> > > be ready before first call. In fact, timekeeping_init() is called early
> > > in start_kernel() which is way before driver_init() (and that's when
> > > devices can start to be initialized) called from rest_init() via
> > > kernel_init_freeable() and do_basic_setup().
> > >
> > This is not (always) correct. My qemu "collie" boot test fails with this
> > patch applied. Reverting the patch fixes the problem. Bisect log attached.
> >
>
> Can you try the patch below ?
> ktime_get_mono_fast_ns() has the advantage of being init with dummy clock so
> it can be used at early_init.

Another possibility would be delay the init of the gpiochip

>
> ---
>  drivers/base/power/runtime.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index ae1c728..118c7f6 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -66,7 +66,7 @@ static int rpm_suspend(struct device *dev, int rpmflags);
>   */
>  void update_pm_runtime_accounting(struct device *dev)
>  {
> -       u64 now = ktime_to_ns(ktime_get());
> +       u64 now = ktime_get_mono_fast_ns();
>         u64 delta;
>
>         delta = now - dev->power.accounting_timestamp;
> @@ -1507,7 +1507,7 @@ void pm_runtime_init(struct device *dev)
>         dev->power.request_pending = false;
>         dev->power.request = RPM_REQ_NONE;
>         dev->power.deferred_resume = false;
> -       dev->power.accounting_timestamp = ktime_to_ns(ktime_get());
> +       dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
>         INIT_WORK(&dev->power.work, pm_runtime_work);
>
>         dev->power.timer_expires = 0;
> --
> 2.7.4
>
>
> > With some added debugging:
> >
> > ...
> > IRQS: 16, nr_irqs: 65, preallocated irqs: 65
> > irq: Cannot allocate irq_descs @ IRQ1, assuming pre-allocated
> > gpio gpiochip0: ############### pm_runtime_init() ############
> > irq: Cannot allocate irq_descs @ IRQ33, assuming pre-allocated
> > ############## timekeeping_init() ####################
> > sched_clock: 32 bits at 3686kHz, resolution 271ns, wraps every 582542222200ns^M
> > ...
> >
> > This is with:
> >
> > void pm_runtime_init(struct device *dev)
> > {
> > +       dev_info(dev, "############### pm_runtime_init() ############\n");
> > +
> > ...
> > @@ -1526,6 +1526,8 @@ void __init timekeeping_init(void)
> >       struct clocksource *clock;
> >       unsigned long flags;
> >
> > +       pr_info("############## timekeeping_init() ####################\n");
> > +
> >
> > Guenter
> >
> > ---
> > # bad: [a37d50ca3b837c19a297f349365d11a20c1087d0] Add linux-next specific files for 20190117
> > # good: [1c7fc5cbc33980acd13d668f1c8f0313d6ae9fd8] Linux 5.0-rc2
> > git bisect start 'HEAD' 'v5.0-rc2'
> > # bad: [4edb817d29fdf19fb5d52784bb3c29c40e00f586] Merge remote-tracking branch 'pm/linux-next'
> > git bisect bad 4edb817d29fdf19fb5d52784bb3c29c40e00f586
> > # good: [6d95886720d306a1914a7c9a8aeb0bcbc7aef018] Merge remote-tracking branch 'omap/for-next'
> > git bisect good 6d95886720d306a1914a7c9a8aeb0bcbc7aef018
> > # good: [975b5cdd74430bc8a04f832d65a47cdb95b73fec] Merge remote-tracking branch 'fuse/for-next'
> > git bisect good 975b5cdd74430bc8a04f832d65a47cdb95b73fec
> > # good: [112386d2189fc54b979c3a8bf64b2908df91e123] Merge remote-tracking branch 'i2c/i2c/for-next'
> > git bisect good 112386d2189fc54b979c3a8bf64b2908df91e123
> > # good: [3943f059823b6e15884387f31618b84826e924b3] media: coda: Add control for h.264 chroma qp index offset
> > git bisect good 3943f059823b6e15884387f31618b84826e924b3
> > # good: [44970bbbbb5079ee100875b06e45db5d6e91a16e] Merge remote-tracking branch 'v4l-dvb/master'
> > git bisect good 44970bbbbb5079ee100875b06e45db5d6e91a16e
> > # bad: [599170c2b860aca3364574f833bb9cc801c9668d] Merge branch 'pm-core' into linux-next
> > git bisect bad 599170c2b860aca3364574f833bb9cc801c9668d
> > # good: [347d570919ca9a3a3653ce9cbb7399c7c0ba8248] Merge branch 'acpi-pci' into linux-next
> > git bisect good 347d570919ca9a3a3653ce9cbb7399c7c0ba8248
> > # good: [e0a9fde86ba1bc26dd754c733b32e70cd8f1c187] Merge branches 'acpi-tables' and 'acpi-apei' into linux-next
> > git bisect good e0a9fde86ba1bc26dd754c733b32e70cd8f1c187
> > # good: [3b4ed2e2eb5583774a1ed4aa4596a5a3c55f2567] drm/i915: Move on the new pm runtime interface
> > git bisect good 3b4ed2e2eb5583774a1ed4aa4596a5a3c55f2567
> > # bad: [c75c303933a68c547f3352d1d708843f9449d3f4] PM: clock_ops: fix missing clk_prepare() return value check
> > git bisect bad c75c303933a68c547f3352d1d708843f9449d3f4
> > # bad: [3982ab9ce433efc72ca31eb9ddc85d9355966444] PM-runtime: Replace jiffies based accounting with ktime-based accounting
> > git bisect bad 3982ab9ce433efc72ca31eb9ddc85d9355966444
> > # first bad commit: [3982ab9ce433efc72ca31eb9ddc85d9355966444] PM-runtime: Replace jiffies based accounting with ktime-based accounting